Polyvinyl Alcohol Enhanced Fluorescent Sulfur Quantum Dots for Highly Sensitive Detection of Fe3+ and Temperature in Cells

Abstract

AbstractAs a new class of metal‐free fluorescent dots, sulfur quantum dots (SQDs) have attracted more and more attention because of their unique properties and promising applications in many fields. However, synthesizing SQDs with high optical stability and stimuli‐responsive fluorescence is still in its infancy. Herein, a simple one‐pot strategy is reported for preparing polyvinyl alcohol (PVA)‐capped SQDs from cheap elemental sulfur by employing PVA as ligand. The as‐prepared SQDs with size in range of 1.5–5 nm show fine water dispersibility and stability, bright fluorescence, good optical stability, and low cytotoxicity, which make them potential for cell imaging. In addition, the SQDs show sensitive and selective fluorescence quenching behavior toward Fe3+ with a detection limit of 92 × 10−9 m. Meanwhile, the SQDs also present temperature‐dependent fluorescence and hold promise for working as a nanothermometer. For the first time, the utilization of SQDs for monitoring of Fe3+ and temperature in the interior of cells is confirmed in this study. This work thus opens new opportunities for expanding the application fields of SQDs.